Apple recently set a release date for iOS 7.0 and Google has announced Android 4.4 KitKat. Meanwhile Microsoft has remained surprisingly silent on the software front, though we know the company is working on the Windows Phone 8.1 (Blue) update alongside the GDR3 update for Windows Phone 8.Not much is known about Windows Phone 8.1, but some new screenshots have revealed a new app grouping feature and a notifications hub.
The first image came from an XDA Developers member, which shows an alleged image Windows Phone 8.1 which was found on an SD card of Nokia Lumia 620 handset. The image displays a notification tile which shows the number of notifications with an '*' indicating that you have new notifications.
Today another alleged image of Windows Phone 8.1 demonstrates app grouping on the homescreen alongside the notification hub. App grouping is a feature available on Windows 8, which allows you to select multiple app tiles and move them together. Windows Phone 8.1 is demonstrated with a similar feature.
Windows Phone 8.1 is expected to be revealed in the first quarter of 2014
source - XDA | WMPowerUser